Hi,
There are enourmously many things here, and thank you for posting.
There might be some systemic engineering problems.
Le 20/01/2020 à 18:21, Rob Brew a écrit :
Dear all.
I have submittetd the following draft RFC for approval.
Obviously whilst underground mobile phone users at public locations,
such as the London underground, will not be able to know their GPS
location, as the GPS signals cannot penetrate the earth.
Except when you can install a GPS repeater.
The problem of lack of ability to penetrate the Earth is known for 4G as
well, and for bluetooth and for wifi.
There are some GPS repeaters in some places. (I did install myself
some). The problem there is the following: make sure you have the right
to do it, license, regulator. Use long but very high-quality cables (RF
- Radio Frequency), which are usually thick and expensive. The GPS
repeater is cheap, 30Euros or so, off the shelf. Use good GPS antennas
in the place where GPS coverage is there, protect from vandalism, tell
others what is good for, for long time. Ideally, write software that
modifies the position to add depth with the known number of meters, to
the GPS signal. That's not really necessary, because people might not
need to orient on 3D, maybe 2D on the same level would be sufficient.
There are some deployments in road tunnels in which Bluetooth devices
are spread along the road underground and claim to repeat localization
in a step-by-step manner. It is a concept, with an IoT device on the
market, but which suffers from systemic engineering problems as well. I
dont think it will fly.
I have submitted a RFC draft at
https://tools.ietf.org/html/draft-brew-intarea-underground-01 to
bypass this problem, as well as a server application in Java at
https://github.com/rydal/underground .
I need to look at it.
Until then, I can tell that there is a GPS GATE software that captures
GPS signals and puts the data (NMEA?) on IP and distributes it to IP
receivers. These IP receivers might be on WiFi too.
In this case, it might be that one needs to tell what is the format of
NMEA over IP. It's very simple.
But, agreeing that NMEA is the best thing is a different thing. On one
hand, NMEA has new versions. But it uses WGS84 which might not be the
best coordinate system - it is good for smartphones and users, maybe
cars, but in some countries it is not used to locate some important
points. These use other coordinate systems. So maybe one wants to come
up with a more universal coordinate system that makes everyone happy,
and take _that_ and put on WiFi (not NMEA). Because, IP is such
universal, we should put universal things on it.
Conversions between systems are huge opportunities for glitches to get
in. These kinds of glitches ahppening very fast and added up may lead,
and have led, to disasters.
As we know the IP Address contacting the server the server contains a
map containing the GPS location of each underground site, as
referenced by IP address. The returns the phsycial GPS location and
name of the site as a JSON array.
To prevent false servers reporting inaccurate information https can
be used to verify the authenticity of the server.
Providing this service to mobile phone user's without a current WIfi
connection i propose going one stage further, create a hidden
wireless network wih the name ".location". In cases where no GPS
location can be found a mobile phone's GPS system can be programmed
to seek such a network providing the same service.
Hold on, 'hidden wireless network', make sure 'hidden terminal problem'
is distinguished.
A phone that cant have WiFi connection - what kind of other IP
connection does it have, in a place that has no GPS coverage? Is it a
cellular connection in underground metro station? If yes, it means
either there are cellular base stations there, or there are cellular
repeaters: enhance them to repeat GPS as well.
This would require alterations to th servics as provided by mobile
phone providers such as Apple and Android.
If you are interested in this concept please review it (and my code),
and maybe it will become something. For a video demonstration of
this service please check the link at the github site.
I will look at the draft later.
Alex
Thanks,
Rob Brew.
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